Merge "Cleanup: Remove passing around of DataPersistenceProvider"
[controller.git] / opendaylight / md-sal / sal-distributed-datastore / src / main / java / org / opendaylight / controller / cluster / datastore / TransactionProxy.java
index 64b9086c250c16f759a417003d0cefc9839f688b..71799c92d40a9bca75304a196f1c500895a04b09 100644 (file)
@@ -12,46 +12,40 @@ import akka.actor.ActorSelection;
 import akka.dispatch.Mapper;
 import akka.dispatch.OnComplete;
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.FinalizablePhantomReference;
-import com.google.common.base.FinalizableReferenceQueue;
 import com.google.common.base.Optional;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.common.util.concurrent.CheckedFuture;
+import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.SettableFuture;
 import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
+import java.util.Set;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicLong;
-import javax.annotation.concurrent.GuardedBy;
 import org.opendaylight.controller.cluster.datastore.compat.PreLithiumTransactionContextImpl;
-import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
 import org.opendaylight.controller.cluster.datastore.identifiers.TransactionIdentifier;
-import org.opendaylight.controller.cluster.datastore.messages.CloseTransaction;
-import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
-import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
 import org.opendaylight.controller.cluster.datastore.shardstrategy.ShardStrategyFactory;
 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
+import org.opendaylight.controller.cluster.datastore.utils.NormalizedNodeAggregator;
 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
+import org.opendaylight.controller.sal.core.spi.data.AbstractDOMStoreTransaction;
 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadWriteTransaction;
-import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
 import org.opendaylight.yangtools.util.concurrent.MappingCheckedFuture;
 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import scala.concurrent.Future;
 import scala.concurrent.Promise;
-import scala.concurrent.duration.FiniteDuration;
 
 /**
  * TransactionProxy acts as a proxy for one or more transactions that were created on a remote shard
@@ -65,12 +59,29 @@ import scala.concurrent.duration.FiniteDuration;
  * shards will be executed.
  * </p>
  */
-public class TransactionProxy implements DOMStoreReadWriteTransaction {
+public class TransactionProxy extends AbstractDOMStoreTransaction<TransactionIdentifier> implements DOMStoreReadWriteTransaction {
 
     public static enum TransactionType {
         READ_ONLY,
         WRITE_ONLY,
-        READ_WRITE
+        READ_WRITE;
+
+        // Cache all values
+        private static final TransactionType[] VALUES = values();
+
+        public static TransactionType fromInt(final int type) {
+            try {
+                return VALUES[type];
+            } catch (IndexOutOfBoundsException e) {
+                throw new IllegalArgumentException("In TransactionType enum value " + type, e);
+            }
+        }
+    }
+
+    private static enum TransactionState {
+        OPEN,
+        READY,
+        CLOSED,
     }
 
     static final Mapper<Throwable, Throwable> SAME_FAILURE_TRANSFORMER =
@@ -85,78 +96,6 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
 
     private static final Logger LOG = LoggerFactory.getLogger(TransactionProxy.class);
 
-    /**
-     * Time interval in between transaction create retries.
-     */
-    private static final FiniteDuration CREATE_TX_TRY_INTERVAL =
-            FiniteDuration.create(1, TimeUnit.SECONDS);
-
-    /**
-     * Used to enqueue the PhantomReferences for read-only TransactionProxy instances. The
-     * FinalizableReferenceQueue is safe to use statically in an OSGi environment as it uses some
-     * trickery to clean up its internal thread when the bundle is unloaded.
-     */
-    private static final FinalizableReferenceQueue phantomReferenceQueue =
-                                                                  new FinalizableReferenceQueue();
-
-    /**
-     * This stores the TransactionProxyCleanupPhantomReference instances statically, This is
-     * necessary because PhantomReferences need a hard reference so they're not garbage collected.
-     * Once finalized, the TransactionProxyCleanupPhantomReference removes itself from this map
-     * and thus becomes eligible for garbage collection.
-     */
-    private static final Map<TransactionProxyCleanupPhantomReference,
-                             TransactionProxyCleanupPhantomReference> phantomReferenceCache =
-                                                                        new ConcurrentHashMap<>();
-
-    /**
-     * A PhantomReference that closes remote transactions for a TransactionProxy when it's
-     * garbage collected. This is used for read-only transactions as they're not explicitly closed
-     * by clients. So the only way to detect that a transaction is no longer in use and it's safe
-     * to clean up is when it's garbage collected. It's inexact as to when an instance will be GC'ed
-     * but TransactionProxy instances should generally be short-lived enough to avoid being moved
-     * to the old generation space and thus should be cleaned up in a timely manner as the GC
-     * runs on the young generation (eden, swap1...) space much more frequently.
-     */
-    private static class TransactionProxyCleanupPhantomReference
-                                           extends FinalizablePhantomReference<TransactionProxy> {
-
-        private final List<ActorSelection> remoteTransactionActors;
-        private final AtomicBoolean remoteTransactionActorsMB;
-        private final ActorContext actorContext;
-        private final TransactionIdentifier identifier;
-
-        protected TransactionProxyCleanupPhantomReference(TransactionProxy referent) {
-            super(referent, phantomReferenceQueue);
-
-            // Note we need to cache the relevant fields from the TransactionProxy as we can't
-            // have a hard reference to the TransactionProxy instance itself.
-
-            remoteTransactionActors = referent.remoteTransactionActors;
-            remoteTransactionActorsMB = referent.remoteTransactionActorsMB;
-            actorContext = referent.actorContext;
-            identifier = referent.identifier;
-        }
-
-        @Override
-        public void finalizeReferent() {
-            LOG.trace("Cleaning up {} Tx actors for TransactionProxy {}",
-                    remoteTransactionActors.size(), identifier);
-
-            phantomReferenceCache.remove(this);
-
-            // Access the memory barrier volatile to ensure all previous updates to the
-            // remoteTransactionActors list are visible to this thread.
-
-            if(remoteTransactionActorsMB.get()) {
-                for(ActorSelection actor : remoteTransactionActors) {
-                    LOG.trace("Sending CloseTransaction to {}", actor);
-                    actorContext.sendOperationAsync(actor, CloseTransaction.INSTANCE.toSerializable());
-                }
-            }
-        }
-    }
-
     /**
      * Stores the remote Tx actors for each requested data store path to be used by the
      * PhantomReference to close the remote Tx's. This is only used for read-only Tx's. The
@@ -164,8 +103,8 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
      * remoteTransactionActors list so they will be visible to the thread accessing the
      * PhantomReference.
      */
-    private List<ActorSelection> remoteTransactionActors;
-    private volatile AtomicBoolean remoteTransactionActorsMB;
+    List<ActorSelection> remoteTransactionActors;
+    volatile AtomicBoolean remoteTransactionActorsMB;
 
     /**
      * Stores the create transaction results per shard.
@@ -173,11 +112,10 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
     private final Map<String, TransactionFutureCallback> txFutureCallbackMap = new HashMap<>();
 
     private final TransactionType transactionType;
-    private final ActorContext actorContext;
-    private final TransactionIdentifier identifier;
+    final ActorContext actorContext;
     private final String transactionChainId;
     private final SchemaContext schemaContext;
-    private boolean inReadyState;
+    private TransactionState state = TransactionState.OPEN;
 
     private volatile boolean initialized;
     private Semaphore operationLimiter;
@@ -187,8 +125,8 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
         this(actorContext, transactionType, "");
     }
 
-    public TransactionProxy(ActorContext actorContext, TransactionType transactionType,
-            String transactionChainId) {
+    public TransactionProxy(ActorContext actorContext, TransactionType transactionType, String transactionChainId) {
+        super(createIdentifier(actorContext));
         this.actorContext = Preconditions.checkNotNull(actorContext,
             "actorContext should not be null");
         this.transactionType = Preconditions.checkNotNull(transactionType,
@@ -197,27 +135,16 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
             "schemaContext should not be null");
         this.transactionChainId = transactionChainId;
 
-        String memberName = actorContext.getCurrentMemberName();
-        if(memberName == null){
-            memberName = "UNKNOWN-MEMBER";
-        }
-
-        this.identifier = new TransactionIdentifier(memberName, counter.getAndIncrement());
-
-        LOG.debug("Created txn {} of type {} on chain {}", identifier, transactionType, transactionChainId);
+        LOG.debug("Created txn {} of type {} on chain {}", getIdentifier(), transactionType, transactionChainId);
     }
 
-    @VisibleForTesting
-    List<Future<Object>> getRecordedOperationFutures() {
-        List<Future<Object>> recordedOperationFutures = Lists.newArrayList();
-        for(TransactionFutureCallback txFutureCallback : txFutureCallbackMap.values()) {
-            TransactionContext transactionContext = txFutureCallback.getTransactionContext();
-            if(transactionContext != null) {
-                recordedOperationFutures.addAll(transactionContext.getRecordedOperationFutures());
-            }
+    private static TransactionIdentifier createIdentifier(ActorContext actorContext) {
+        String memberName = actorContext.getCurrentMemberName();
+        if (memberName == null) {
+            memberName = "UNKNOWN-MEMBER";
         }
 
-        return recordedOperationFutures;
+        return new TransactionIdentifier(memberName, counter.getAndIncrement());
     }
 
     @VisibleForTesting
@@ -232,36 +159,81 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
         return false;
     }
 
+    private boolean isRootPath(YangInstanceIdentifier path){
+        return !path.getPathArguments().iterator().hasNext();
+    }
+
     @Override
     public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
 
         Preconditions.checkState(transactionType != TransactionType.WRITE_ONLY,
                 "Read operation on write-only transaction is not allowed");
 
-        LOG.debug("Tx {} read {}", identifier, path);
-
-        throttleOperation();
+        LOG.debug("Tx {} read {}", getIdentifier(), path);
 
         final SettableFuture<Optional<NormalizedNode<?, ?>>> proxyFuture = SettableFuture.create();
 
-        TransactionFutureCallback txFutureCallback = getOrCreateTxFutureCallback(path);
-        txFutureCallback.enqueueTransactionOperation(new TransactionOperation() {
-            @Override
-            public void invoke(TransactionContext transactionContext) {
-                transactionContext.readData(path, proxyFuture);
-            }
-        });
+        if(isRootPath(path)){
+            readAllData(path, proxyFuture);
+        } else {
+            throttleOperation();
+
+            TransactionFutureCallback txFutureCallback = getOrCreateTxFutureCallback(path);
+            txFutureCallback.enqueueTransactionOperation(new TransactionOperation() {
+                @Override
+                public void invoke(TransactionContext transactionContext) {
+                    transactionContext.readData(path, proxyFuture);
+                }
+            });
+
+        }
 
         return MappingCheckedFuture.create(proxyFuture, ReadFailedException.MAPPER);
     }
 
+    private void readAllData(final YangInstanceIdentifier path,
+                             final SettableFuture<Optional<NormalizedNode<?, ?>>> proxyFuture) {
+        Set<String> allShardNames = actorContext.getConfiguration().getAllShardNames();
+        List<SettableFuture<Optional<NormalizedNode<?, ?>>>> futures = new ArrayList<>(allShardNames.size());
+
+        for(String shardName : allShardNames){
+            final SettableFuture<Optional<NormalizedNode<?, ?>>> subProxyFuture = SettableFuture.create();
+
+            throttleOperation();
+
+            TransactionFutureCallback txFutureCallback = getOrCreateTxFutureCallback(shardName);
+            txFutureCallback.enqueueTransactionOperation(new TransactionOperation() {
+                @Override
+                public void invoke(TransactionContext transactionContext) {
+                    transactionContext.readData(path, subProxyFuture);
+                }
+            });
+
+            futures.add(subProxyFuture);
+        }
+
+        final ListenableFuture<List<Optional<NormalizedNode<?, ?>>>> future = Futures.allAsList(futures);
+
+        future.addListener(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    proxyFuture.set(NormalizedNodeAggregator.aggregate(YangInstanceIdentifier.builder().build(),
+                            future.get(), actorContext.getSchemaContext()));
+                } catch (DataValidationFailedException | InterruptedException | ExecutionException e) {
+                    proxyFuture.setException(e);
+                }
+            }
+        }, actorContext.getActorSystem().dispatcher());
+    }
+
     @Override
     public CheckedFuture<Boolean, ReadFailedException> exists(final YangInstanceIdentifier path) {
 
         Preconditions.checkState(transactionType != TransactionType.WRITE_ONLY,
                 "Exists operation on write-only transaction is not allowed");
 
-        LOG.debug("Tx {} exists {}", identifier, path);
+        LOG.debug("Tx {} exists {}", getIdentifier(), path);
 
         throttleOperation();
 
@@ -281,7 +253,7 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
     private void checkModificationState() {
         Preconditions.checkState(transactionType != TransactionType.READ_ONLY,
                 "Modification operation on read-only transaction is not allowed");
-        Preconditions.checkState(!inReadyState,
+        Preconditions.checkState(state == TransactionState.OPEN,
                 "Transaction is sealed - further modifications are not allowed");
     }
 
@@ -314,13 +286,16 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
         }
     }
 
+    final void ensureInitializied() {
+        Preconditions.checkState(initialized, "Transaction %s was not propertly initialized.", getIdentifier());
+    }
 
     @Override
     public void write(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
 
         checkModificationState();
 
-        LOG.debug("Tx {} write {}", identifier, path);
+        LOG.debug("Tx {} write {}", getIdentifier(), path);
 
         throttleOperation();
 
@@ -338,7 +313,7 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
 
         checkModificationState();
 
-        LOG.debug("Tx {} merge {}", identifier, path);
+        LOG.debug("Tx {} merge {}", getIdentifier(), path);
 
         throttleOperation();
 
@@ -356,7 +331,7 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
 
         checkModificationState();
 
-        LOG.debug("Tx {} delete {}", identifier, path);
+        LOG.debug("Tx {} delete {}", getIdentifier(), path);
 
         throttleOperation();
 
@@ -369,28 +344,37 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
         });
     }
 
-    @Override
-    public DOMStoreThreePhaseCommitCohort ready() {
+    private boolean seal(final TransactionState newState) {
+        if (state == TransactionState.OPEN) {
+            state = newState;
+            return true;
+        } else {
+            return false;
+        }
+    }
 
-        checkModificationState();
+    @Override
+    public AbstractThreePhaseCommitCohort ready() {
+        Preconditions.checkState(transactionType != TransactionType.READ_ONLY,
+                "Read-only transactions cannot be readied");
 
-        inReadyState = true;
+        final boolean success = seal(TransactionState.READY);
+        Preconditions.checkState(success, "Transaction %s is %s, it cannot be readied", getIdentifier(), state);
 
-        LOG.debug("Tx {} Readying {} transactions for commit", identifier,
+        LOG.debug("Tx {} Readying {} transactions for commit", getIdentifier(),
                     txFutureCallbackMap.size());
 
-        if(txFutureCallbackMap.size() == 0) {
-            onTransactionReady(Collections.<Future<ActorSelection>>emptyList());
+        if (txFutureCallbackMap.isEmpty()) {
+            TransactionRateLimitingCallback.adjustRateLimitForUnusedTransaction(actorContext);
             return NoOpDOMStoreThreePhaseCommitCohort.INSTANCE;
         }
 
         throttleOperation(txFutureCallbackMap.size());
 
-        List<Future<ActorSelection>> cohortFutures = Lists.newArrayList();
-
+        List<Future<ActorSelection>> cohortFutures = new ArrayList<>(txFutureCallbackMap.size());
         for(TransactionFutureCallback txFutureCallback : txFutureCallbackMap.values()) {
 
-            LOG.debug("Tx {} Readying transaction for shard {} chain {}", identifier,
+            LOG.debug("Tx {} Readying transaction for shard {} chain {}", getIdentifier(),
                         txFutureCallback.getShardName(), transactionChainId);
 
             final TransactionContext transactionContext = txFutureCallback.getTransactionContext();
@@ -412,27 +396,22 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
             cohortFutures.add(future);
         }
 
-        onTransactionReady(cohortFutures);
-
         return new ThreePhaseCommitCohortProxy(actorContext, cohortFutures,
-                identifier.toString());
-    }
-
-    /**
-     * Method for derived classes to be notified when the transaction has been readied.
-     *
-     * @param cohortFutures the cohort Futures for each shard transaction.
-     */
-    protected void onTransactionReady(List<Future<ActorSelection>> cohortFutures) {
-    }
-
-    @Override
-    public Object getIdentifier() {
-        return this.identifier;
+            getIdentifier().toString());
     }
 
     @Override
     public void close() {
+        if (!seal(TransactionState.CLOSED)) {
+            if (state == TransactionState.CLOSED) {
+                // Idempotent no-op as per AutoCloseable recommendation
+                return;
+            }
+
+            throw new IllegalStateException(String.format("Transaction %s is ready, it cannot be closed",
+                getIdentifier()));
+        }
+
         for (TransactionFutureCallback txFutureCallback : txFutureCallbackMap.values()) {
             txFutureCallback.enqueueTransactionOperation(new TransactionOperation() {
                 @Override
@@ -458,13 +437,25 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
         return actorContext.findPrimaryShardAsync(shardName);
     }
 
+    final TransactionType getTransactionType() {
+        return transactionType;
+    }
+
+    final Semaphore getOperationLimiter() {
+        return operationLimiter;
+    }
+
     private TransactionFutureCallback getOrCreateTxFutureCallback(YangInstanceIdentifier path) {
         String shardName = shardNameFromIdentifier(path);
+        return getOrCreateTxFutureCallback(shardName);
+    }
+
+    private TransactionFutureCallback getOrCreateTxFutureCallback(String shardName) {
         TransactionFutureCallback txFutureCallback = txFutureCallbackMap.get(shardName);
         if(txFutureCallback == null) {
             Future<ActorSelection> findPrimaryFuture = sendFindPrimaryShardAsync(shardName);
 
-            final TransactionFutureCallback newTxFutureCallback = new TransactionFutureCallback(shardName);
+            final TransactionFutureCallback newTxFutureCallback = new TransactionFutureCallback(this, shardName);
 
             txFutureCallback = newTxFutureCallback;
             txFutureCallbackMap.put(shardName, txFutureCallback);
@@ -473,7 +464,7 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
                 @Override
                 public void onComplete(Throwable failure, ActorSelection primaryShard) {
                     if(failure != null) {
-                        newTxFutureCallback.onComplete(failure, null);
+                        newTxFutureCallback.createTransactionContext(failure, null);
                     } else {
                         newTxFutureCallback.setPrimaryShard(primaryShard);
                     }
@@ -484,7 +475,7 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
         return txFutureCallback;
     }
 
-    public String getTransactionChainId() {
+    String getTransactionChainId() {
         return transactionChainId;
     }
 
@@ -492,273 +483,41 @@ public class TransactionProxy implements DOMStoreReadWriteTransaction {
         return actorContext;
     }
 
-    /**
-     * Interfaces for transaction operations to be invoked later.
-     */
-    private static interface TransactionOperation {
-        void invoke(TransactionContext transactionContext);
-    }
-
-    /**
-     * Implements a Future OnComplete callback for a CreateTransaction message. This class handles
-     * retries, up to a limit, if the shard doesn't have a leader yet. This is done by scheduling a
-     * retry task after a short delay.
-     * <p>
-     * The end result from a completed CreateTransaction message is a TransactionContext that is
-     * used to perform transaction operations. Transaction operations that occur before the
-     * CreateTransaction completes are cache and executed once the CreateTransaction completes,
-     * successfully or not.
-     */
-    private class TransactionFutureCallback extends OnComplete<Object> {
-
-        /**
-         * The list of transaction operations to execute once the CreateTransaction completes.
-         */
-        @GuardedBy("txOperationsOnComplete")
-        private final List<TransactionOperation> txOperationsOnComplete = Lists.newArrayList();
-
-        /**
-         * The TransactionContext resulting from the CreateTransaction reply.
-         */
-        private volatile TransactionContext transactionContext;
-
-        /**
-         * The target primary shard.
-         */
-        private volatile ActorSelection primaryShard;
-
-        private volatile int createTxTries = (int) (actorContext.getDatastoreContext().
-                getShardLeaderElectionTimeout().duration().toMillis() /
-                CREATE_TX_TRY_INTERVAL.toMillis());
-
-        private final String shardName;
-
-        TransactionFutureCallback(String shardName) {
-            this.shardName = shardName;
-        }
-
-        String getShardName() {
-            return shardName;
-        }
-
-        TransactionContext getTransactionContext() {
-            return transactionContext;
-        }
-
-
-        /**
-         * Sets the target primary shard and initiates a CreateTransaction try.
-         */
-        void setPrimaryShard(ActorSelection primaryShard) {
-            LOG.debug("Tx {} Primary shard found - trying create transaction", identifier);
-
-            this.primaryShard = primaryShard;
-            tryCreateTransaction();
-        }
-
-        /**
-         * Adds a TransactionOperation to be executed after the CreateTransaction completes.
-         */
-        void addTxOperationOnComplete(TransactionOperation operation) {
-            boolean invokeOperation = true;
-            synchronized(txOperationsOnComplete) {
-                if(transactionContext == null) {
-                    LOG.debug("Tx {} Adding operation on complete {}", identifier);
-
-                    invokeOperation = false;
-                    txOperationsOnComplete.add(operation);
-                }
-            }
-
-            if(invokeOperation) {
-                operation.invoke(transactionContext);
-            }
-        }
-
-        void enqueueTransactionOperation(final TransactionOperation op) {
-
-            if (transactionContext != null) {
-                op.invoke(transactionContext);
-            } else {
-                // The shard Tx hasn't been created yet so add the Tx operation to the Tx Future
-                // callback to be executed after the Tx is created.
-                addTxOperationOnComplete(op);
-            }
-        }
-
-        /**
-         * Performs a CreateTransaction try async.
-         */
-        private void tryCreateTransaction() {
-            Object serializedCreateMessage = new CreateTransaction(identifier.toString(),
-                    TransactionProxy.this.transactionType.ordinal(),
-                    getTransactionChainId()).toSerializable();
-
-            Future<Object> createTxFuture = actorContext.executeOperationAsync(primaryShard, serializedCreateMessage);
-
-            createTxFuture.onComplete(this, actorContext.getClientDispatcher());
-        }
-
-        @Override
-        public void onComplete(Throwable failure, Object response) {
-            if(failure instanceof NoShardLeaderException) {
-                // There's no leader for the shard yet - schedule and try again, unless we're out
-                // of retries. Note: createTxTries is volatile as it may be written by different
-                // threads however not concurrently, therefore decrementing it non-atomically here
-                // is ok.
-                if(--createTxTries > 0) {
-                    LOG.debug("Tx {} Shard {} has no leader yet - scheduling create Tx retry",
-                            identifier, shardName);
-
-                    actorContext.getActorSystem().scheduler().scheduleOnce(CREATE_TX_TRY_INTERVAL,
-                            new Runnable() {
-                                @Override
-                                public void run() {
-                                    tryCreateTransaction();
-                                }
-                            }, actorContext.getClientDispatcher());
-                    return;
-                }
-            }
-
-            // Mainly checking for state violation here to perform a volatile read of "initialized" to
-            // ensure updates to operationLimter et al are visible to this thread (ie we're doing
-            // "piggy-back" synchronization here).
-            Preconditions.checkState(initialized, "Tx was not propertly initialized.");
-
-            // Create the TransactionContext from the response or failure. Store the new
-            // TransactionContext locally until we've completed invoking the
-            // TransactionOperations. This avoids thread timing issues which could cause
-            // out-of-order TransactionOperations. Eg, on a modification operation, if the
-            // TransactionContext is non-null, then we directly call the TransactionContext.
-            // However, at the same time, the code may be executing the cached
-            // TransactionOperations. So to avoid thus timing, we don't publish the
-            // TransactionContext until after we've executed all cached TransactionOperations.
-            TransactionContext localTransactionContext;
-            if(failure != null) {
-                LOG.debug("Tx {} Creating NoOpTransaction because of error: {}", identifier,
-                        failure.getMessage());
-
-                localTransactionContext = new NoOpTransactionContext(failure, identifier, operationLimiter);
-            } else if (response.getClass().equals(CreateTransactionReply.SERIALIZABLE_CLASS)) {
-                localTransactionContext = createValidTransactionContext(
-                        CreateTransactionReply.fromSerializable(response));
-            } else {
-                IllegalArgumentException exception = new IllegalArgumentException(String.format(
-                        "Invalid reply type %s for CreateTransaction", response.getClass()));
-
-                localTransactionContext = new NoOpTransactionContext(exception, identifier, operationLimiter);
-            }
-
-            executeTxOperatonsOnComplete(localTransactionContext);
-        }
-
-        private void executeTxOperatonsOnComplete(TransactionContext localTransactionContext) {
-            while(true) {
-                // Access to txOperationsOnComplete and transactionContext must be protected and atomic
-                // (ie synchronized) with respect to #addTxOperationOnComplete to handle timing
-                // issues and ensure no TransactionOperation is missed and that they are processed
-                // in the order they occurred.
-
-                // We'll make a local copy of the txOperationsOnComplete list to handle re-entrancy
-                // in case a TransactionOperation results in another transaction operation being
-                // queued (eg a put operation from a client read Future callback that is notified
-                // synchronously).
-                Collection<TransactionOperation> operationsBatch = null;
-                synchronized(txOperationsOnComplete) {
-                    if(txOperationsOnComplete.isEmpty()) {
-                        // We're done invoking the TransactionOperations so we can now publish the
-                        // TransactionContext.
-                        transactionContext = localTransactionContext;
-                        break;
-                    }
-
-                    operationsBatch = new ArrayList<>(txOperationsOnComplete);
-                    txOperationsOnComplete.clear();
-                }
-
-                // Invoke TransactionOperations outside the sync block to avoid unnecessary blocking.
-                // A slight down-side is that we need to re-acquire the lock below but this should
-                // be negligible.
-                for(TransactionOperation oper: operationsBatch) {
-                    oper.invoke(localTransactionContext);
-                }
-            }
-        }
-
-        private TransactionContext createValidTransactionContext(CreateTransactionReply reply) {
-            String transactionPath = reply.getTransactionPath();
+    TransactionContext createValidTransactionContext(ActorSelection transactionActor,
+            String transactionPath, short remoteTransactionVersion) {
 
-            LOG.debug("Tx {} Received {}", identifier, reply);
+        if (transactionType == TransactionType.READ_ONLY) {
+            // Read-only Tx's aren't explicitly closed by the client so we create a PhantomReference
+            // to close the remote Tx's when this instance is no longer in use and is garbage
+            // collected.
 
-            ActorSelection transactionActor = actorContext.actorSelection(transactionPath);
+            if(remoteTransactionActorsMB == null) {
+                remoteTransactionActors = Lists.newArrayList();
+                remoteTransactionActorsMB = new AtomicBoolean();
 
-            if (transactionType == TransactionType.READ_ONLY) {
-                // Read-only Tx's aren't explicitly closed by the client so we create a PhantomReference
-                // to close the remote Tx's when this instance is no longer in use and is garbage
-                // collected.
-
-                if(remoteTransactionActorsMB == null) {
-                    remoteTransactionActors = Lists.newArrayList();
-                    remoteTransactionActorsMB = new AtomicBoolean();
-
-                    TransactionProxyCleanupPhantomReference cleanup =
-                            new TransactionProxyCleanupPhantomReference(TransactionProxy.this);
-                    phantomReferenceCache.put(cleanup, cleanup);
-                }
-
-                // Add the actor to the remoteTransactionActors list for access by the
-                // cleanup PhantonReference.
-                remoteTransactionActors.add(transactionActor);
-
-                // Write to the memory barrier volatile to publish the above update to the
-                // remoteTransactionActors list for thread visibility.
-                remoteTransactionActorsMB.set(true);
-            }
-
-            // TxActor is always created where the leader of the shard is.
-            // Check if TxActor is created in the same node
-            boolean isTxActorLocal = actorContext.isPathLocal(transactionPath);
-
-            if(reply.getVersion() >= DataStoreVersions.LITHIUM_VERSION) {
-                return new TransactionContextImpl(transactionPath, transactionActor, identifier,
-                    actorContext, schemaContext, isTxActorLocal, reply.getVersion(), operationCompleter);
-            } else {
-                return new PreLithiumTransactionContextImpl(transactionPath, transactionActor, identifier,
-                        actorContext, schemaContext, isTxActorLocal, reply.getVersion(), operationCompleter);
+                TransactionProxyCleanupPhantomReference.track(TransactionProxy.this);
             }
-        }
-    }
-
-    private static class NoOpDOMStoreThreePhaseCommitCohort implements DOMStoreThreePhaseCommitCohort {
-        static NoOpDOMStoreThreePhaseCommitCohort INSTANCE = new NoOpDOMStoreThreePhaseCommitCohort();
 
-        private static final ListenableFuture<Void> IMMEDIATE_VOID_SUCCESS =
-                com.google.common.util.concurrent.Futures.immediateFuture(null);
-        private static final ListenableFuture<Boolean> IMMEDIATE_BOOLEAN_SUCCESS =
-                com.google.common.util.concurrent.Futures.immediateFuture(Boolean.TRUE);
+            // Add the actor to the remoteTransactionActors list for access by the
+            // cleanup PhantonReference.
+            remoteTransactionActors.add(transactionActor);
 
-        private NoOpDOMStoreThreePhaseCommitCohort() {
-        }
-
-        @Override
-        public ListenableFuture<Boolean> canCommit() {
-            return IMMEDIATE_BOOLEAN_SUCCESS;
-        }
-
-        @Override
-        public ListenableFuture<Void> preCommit() {
-            return IMMEDIATE_VOID_SUCCESS;
-        }
-
-        @Override
-        public ListenableFuture<Void> abort() {
-            return IMMEDIATE_VOID_SUCCESS;
+            // Write to the memory barrier volatile to publish the above update to the
+            // remoteTransactionActors list for thread visibility.
+            remoteTransactionActorsMB.set(true);
         }
 
-        @Override
-        public ListenableFuture<Void> commit() {
-            return IMMEDIATE_VOID_SUCCESS;
+        // TxActor is always created where the leader of the shard is.
+        // Check if TxActor is created in the same node
+        boolean isTxActorLocal = actorContext.isPathLocal(transactionPath);
+
+        if(remoteTransactionVersion < DataStoreVersions.LITHIUM_VERSION) {
+            return new PreLithiumTransactionContextImpl(transactionPath, transactionActor, getIdentifier(),
+                    transactionChainId, actorContext, schemaContext, isTxActorLocal, remoteTransactionVersion,
+                    operationCompleter);
+        } else {
+            return new TransactionContextImpl(transactionActor, getIdentifier(), transactionChainId,
+                    actorContext, schemaContext, isTxActorLocal, remoteTransactionVersion, operationCompleter);
         }
     }
 }